Film holder



Feb. 1, 1966 a. EISENBERG 3,232,203

FILM HOLDER Filed May '7, 1963 FIG. I

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United States Patent O",

332,203 FILM HOLDER Ben Eisenberg, Larchmont, N.Y., assignor to Lclrtra Laboratories, Inc, New York, N.Y., a corporation of New York Filed May 7, 1963, Ser. No. 278,666 1 Claim. (Cl. 9510il) This invention is related to a device for holding film during the development thereof.

A general object of this invention is to provide a film holder which places the film under tension in longitudinal and transverse direction so as to hold it taut in a common plane.

Another object of this invention is to provide a device of this type having a frame adapted to be supported in the usual manner in channels in a film developing tank and having four film gripping devices and means for resiliently urging said gripping devices along lines at right angles to each other to place the film under longitudinal and transverse tension.

Other more detailed object-s of the invention will be apparent from the following disclosure of the single em.- -bodiment thereof illustrated in the attached drawings.

In those drawings- FIGURE 1 is a side elevational View of the film holder of this invention;

FIGURE 2 is a similar view showing a film mounted therein; and

FIGURE 3 is a detailed cross-sectional view taken on the line 3-3 of FIGURE 2.

In the development of photographic film and more particularly in the development of color negatives, it is important that the film he held fiat, that is, in a single common plane, and to maintain this condition when the film buckles due to its immersion in the developing liquid.

Film holders now used for this purpose do not hold the film flat, with the result that the developed film often shows streaks, scratches, and frequently has a mottled appearance. As is well understood in the art the developing fluid is caused in various ways to circulate during the development of the film, so as to continuously bring fresh developer into contact with the film emulsion. Proper contact is interfered with if the film buckles, which it tends to do if it is not held under tension. It can be readily understood that the developing fiuid circulates more freely and fresh fluid is brought into contact with the emulsion more effectively if the film presents a flat plane surface.

A plurality of these film holders are usually mounted in the developing tank so that the films held therein lie in generally parallel planes providing channels through which the developing fluid circulates. If the film is loose or sags due to wetting the spaces between the film present irregular channels which interfere with free and uniform circulation of the fluid therebetween. These difficulties are avoided by the means of the film holder of this invention. As illustrated, it comprises an open side frame, in this case blown up, composed of a top bar it) and a pair of side frame bars 12 and 14. One end of each of the bars is bent up at right angles and welded to the under side of the top bar as shown. The other ends of the side bars 12 and 14 are cross connected by a strut which may be a wire 16 of sufficient gauge to make it rigid under the conditions of use. As a result the mem- 3,232,203 Patented Feb. 1,1966

*bers 10, 1 2, 14 and 16 .form an open-sided generally rectangular "frame which can be supported on .the sides of the tank by means of the ends of the top bar 10 which overhang the side bars as shown.

Secured to the undersurface of the top bar 10 at its center is a unitary leaf spring comprising several sections. The central section 18 is U-shaped and is welded to the undersurface of the bar 10. Extending in opposite directions from the ends of the central section are a pair of arms 20 and 22, the ends of which are bent downwardly at right angles as shown. Slidably mounted in apertures at the ends of the arms 29 and 22 is a rod 24 which has its ends upset as shown so that it cannot escape. Slidably mounted on the rod 24 are a pair of spring clips or film gripping devices 26 and 28. Interposed between the clips 26 and 28 and mounted on the rod 24 are a pair of coil springs 32 and 32 which seat at their opposite ends against abutments formed by distorting the rod 24 as shown at 24a and 24b.

Mounted on the rod 16 adjacent the side member 12 is a third spring clip or film gripping device 34 which is fastened to the rod in any suitable manner. Slidably mounted towards the other end of rod 16 is a fourth spring clip or film gripping device 36. Bearing on the clip 36 is a coil spring 38 surrounding the rod 16 and seatcai at its other end on an abutment 16a provided be deforming the rod 16.

At this point it may be noted that the clips 26, 28, 34 and 36 are per se of no novelty being a common type of gripping device comprising a pair of hingedly connected gripping fingers urged to gripping position by means of springs not shown. Referring to FIGURE 3,

it will be seen that by pinching the end of the clips 26 7 adjacent the rod 16 its jaws will open so that the film F can be gripped at its edges.

Referring to FIGURE 2, the relationship of the parts is shown when film F is mounted in the film gripping devices. To mount the film F the clips 26 and 28 are moved towards each other to partially compress the springs 39 and 32 respectively and then are clamped to the upper edge of the film F. When released the springs urge the clips 26 and Z8 outwardly to place the upper edge of the film under longitudinal tension. The film is then moved downwardly causing the leaf spring arms 2d and 22 to be stressed downwardly from the position shown in FIGURE 1 to the position shown in FIGURE 2, until it is possible to grip the lower edge of the film in the clip 34. The clip 36 is then moved to the left to partially compress the spring 38 and it, in turn, is caused to clamp the adjacent edge of the film F. When the film is relieved of all external forces it will be seen that it is stressed longitudinally along its lower edge and pulled transversely or upwardly by the leaf spring arms 29 and 22. In other words, the stressed leaf spring arms 20 and 22 and the loaded springs 30, 32 and 38 simultaneously place the film F under tension longitudinally and transversely. Thus, the film is held taut in a common plane. Even after it has been immersed in the developing solution any tendency to stretch is absorbed by the spring loading so that the film remains flat under all normal developing conditions.

From the above disclosures it will be apparent to those skilled in the art wherein the novelty of this film holder resides. It will be equally apparent that the particular embodiment selected for illustrative purposes is 3 d capable of variation in its details of construction. It is causing said second pair 'of clamps to apply tension to preferred therefore that the scope of protection afforded the film parallel to said second edge and simultaneously hereby be determined by the appended claim and not apply tension to the film parallel to its longitudinal edges. limited to that illustrative embodiment.

What is claimed; 5 References Cited by the Examiner A film holder comprising a rectangular planar frame, UNITED STATES PATENTS means including a pan of film clamps gripping a rectangu- 1,929,283 10/1933 Miner 95 1Q0 lar photographic film sheet at spaced points along one 2 9 77 10 19 2 W lf 5 100 transverse edge, means for causing said clamps to apply 2,579,2 7 12 1951 Al 95 100 i'tension to the film parallel to said edge, means including 19 3,100,326 8/1963 Buck 95-l00 a second pair of clamps for gripping the film at spaced points along its other transverse edge and means for NORTON ANSHER, Primary Examiner- 

